This invention relates to an optical parametric oscillator using a nonlinear optical crystal.
An optical parametric oscillator of the type described, generally includes a laser medium for producing a fundamental wave of a fundamental wavelength. A pair of optical elements are opposed to each other with the laser medium interposed therebetween. The optical elements constitute a resonator exhibiting resonance for the fundamental wave. Located between the optical elements, a nonlinear optical crystal carries out wavelength-conversion on the the fundamental wave to produce a wavelength-converted wave of a converted wavelength so that one of the optical elements transmits the wavelength-converted wave as an oscillator output wave.
A conventional optical parametric oscillator is disclosed in Japanese Unexamined Patent Publication No. 164048/1994. As will later be described, the conventional optical parametric oscillator is incapable of achieving a high-efficiency wavelength conversion because it is impossible to suppress undesirable succeeding oscillation of the wavelength-converted wave which oscillation inevitably occurs due to oscillation of the fundamental wave of a lower intensity after main oscillation of the wavelength-converted wave occurs due to oscillation of the fundamental wave of a higher intensity.